This entry states the total route length of the railway network and of its component parts by gauge, which is the measure of the distance between the inner sides of the load-bearing rails. The four typical types of gauges are: broad, standard, narrow, and dual. Other gauges are listed under note. Some 60% of the world's railways use the standard gauge of 1.4 m (4.7 ft). Gauges vary by country and sometimes within countries. The choice of gauge during initial construction was mainly in response to local conditions and the intent of the builder. Narrow-gauge railways were cheaper to build and could negotiate sharper curves, broad-gauge railways gave greater stability and permitted higher speeds. Standard-gauge railways were a compromise between narrow and broad gauges.

total: 18 kmstandard gauge: 18 km 1.435-m (not in operation)note: the 18-km Christmas Island Phosphate Company Railway between Flying Fish Cove and South Point was decommissioned in 1987; some tracks and scrap remain in place (2017)

total: 278 kmnarrow gauge: 278 km 1.067-m gaugenote: the entire rail network fell into disrepair and out of use at the end of the 20th century; since 2005, certain sections of rail have been rehabilitated (2014)

total: 800 kmnarrow gauge: 800 km 0.914-m gaugenote: despite the existence of a railway network, all rail service was suspended in 2007 and no passenger or freight train currently runs in the country (2018)

total: 429 kmstandard gauge: 345 km 1.435-m gaugenarrow gauge: 84 km 1.067-m gaugenote: most sections of the railways inoperable due to damage sustained during the civil wars from 1980 to 2003, but many are being rebuilt (2008)

total: 248 kmnote: a narrow gauge, single-track railroad between Babonosa (Sudan) and Wau, the only existing rail system, was repaired in 2010 with $250 million in UN funds, but is not currently operational (2018)